A navigation system mounted on a vehicle generally offers guidance for a route from a departure point to a destination by voice or images, for example. For route guidance, if a driver inputs the name, address, telephone number and the like of a target point through an input device or the like of the navigation system, the navigation system sets the input point as a destination. Then, for driving assistance, the navigation system provides guidance along a route from the current position of the vehicle to the set destination together with surrounding traffic information, for example.
As an example, a system described in Patent Document 1 has been considered to be used as a device for such route search. The system described in Patent Document 1 acquires position information in message information such as that on Twitter (registered trademark) transmitted from a server and searches for a route to a point indicated by the acquired position information. Then, based on route information about the searched route, this system offers the route guidance to the point indicated by the position information.